1. Field of the Invention
The present invention relates to a gas turbine moving blade platform constructed so as to enhance a cooling performance thereof.
2. Description of the Prior Art
FIG. 8 is a cross sectional view of a representative prior art gas turbine moving blade platform. In FIG. 8, numeral 80 designates a platform in its entire form and numeral 51 designates a first stage moving blade. Numeral 52 designates a leading edge passage of the moving blade 51 and cooling passages 83, 84 are communicated with the leading edge passage 52 and extending toward respective side portions of the platform 80. The cooling passages 83, 84 connected to cooling passages 85, 86, respectively, on both side portions and the cooling passages 85, 86 open at a rear end of the platform 80 so that cooling air 70 is blown therefrom, respectively.
Cooling passages 87 and 88, 89 and 90 are provided in a front portion of the platform 80, on both sides thereof and the cooling passages 88 to 90 are bored at an angle from a lower surface toward an upper surface of the platform 80 so as to open at the upper surface so that cooling air is blown therefrom. Also, cooling passages 91, 92, 93 are bored in a rear portion of the platform 80 so as to extend likewise at an angle from the lower surface toward the upper surface of the platform 80 and to open at the rear end thereof so that the cooling air is blown therefrom.
Further, in a central portion of the platform 80, there are provided cooling passages 94, 95, 96, 97, 98 and these cooling passages are also bored at an angle from the lower surface toward the upper surface of the platform 80 so that the cooling air is blown from the upper surface. An outlet end portion of each of the cooling passages 94 to 98 is worked so as to be enlarged in a funnel-like shape so that the cooling air is diffused over the upper surface.
FIG. 9 is a contracted cross sectional view taken on line 9--9 of FIG. 8, wherein the cooling passages 85, 86 are provided in both side portions of the platform 80 and the cooling passage 97 is bored at an angle from the lower surface toward the upper surface of the platform 80.
FIG. 10 is a contracted cross sectional view taken on line 10--10 of FIG. 8, wherein there are provided the cooling passage 85 extending from the front portion toward the rear portion of the platform 80 so as to open at the rear end, and the cooling passages 87, 94 to 98 extend angularly so that the cooling air is blown therethrough rearwardly and upwardly, respectively.
In the platform 80, constructed as above, cooling air which has been supplied into the moving blade 51 through the leading edge passage 52 flows portionally into the cooling passages 85, 86 for cooling of both side portions of the platform 80 to then flow out of the rear end of the platform 80. Also, the cooling passages 87 to 90, 91 to 93, respectively, are inclined in the front and rear portions of the platform 80 so that cooling air is introduced thereinto from the lower surface of the platform 80 so as to flow out of the upper surface of the front and rear end portions of the platform 80. Further, the cooling passages 94 to 98 are inclined in the central portion and cooling air flows therethrough from the lower surface of the platform 80 and out of the upper surface thereof. Thus, the entire portion of the platform 80 is cooled by the cooling air flowing therein and flowing out thereof.
In the representative prior art gas turbine moving blade platform as described above, there are provided linearly extending main cooling passages of the cooling passages 85, 86, and in addition thereto, there are provided a multiplicity of cooling passages of the cooling passages 87 to 90, 91 to 93, etc. which pass through the platform 80 at an angle and thus have a comparatively long inclined route. Hence, in the platform 80, there are provided many such cooling air supply passages and processing or working of the platform itself becomes complicated, and thus it is necessary to develop a cooling structure for the platform which can be made simpler and still has an excellent cooling effect that will cool an entire portion of the platform uniformly.